Blind sleeps accumulate serially (no t.Parallel anywhere) and inflate
under the race detector's scheduling overhead — contributing to the
~136s channelserver test run time.
Replace ~75 arbitrary sleeps (50ms–1s) across 7 test files with 2s
polling loops that exit as soon as the expected condition holds. Sleeps
that are genuinely intentional (race-condition stress tests, cache
expiry, temporal spacing in timestamp tests, backpressure pacing) are
left untouched.
The test ran handleMsgMhfSavedata and logoutPlayer concurrently on the
same session, triggering data races on s.playtime and Save(). In
production the dispatch loop processes packets sequentially per session,
so this overlap is impossible. Run the operations sequentially to match
real behavior while still validating no data loss.
- testhelpers_db: retry truncateAllTables up to 3 times on deadlock,
which occurs when previous tests' goroutines still hold DB connections
- handlers_rengoku_integration_test: restore rengoku_score table after
TestRengokuData_SaveOnDBError drops it, preventing cascading failures
in all subsequent rengoku tests
- client_connection_simulation_test: fix TestClientConnection_PacketDuringLogout
to accept both race outcomes (save-wins or logout-wins) since both
handlers independently load from DB and last-writer-wins is valid
